I've read a bunch of contradictory information both here and other places. Obviously, originally, only up to 2 gig cards were supported. I've seen people say that they now can use larger cards if formatted in a computer instead of the camera.

I'm looking to pick up a 1Dsii rather than a 5Dii to go with my 5D and just want to be prepared. Thanks.

Well, I changed my mind at the last minute. I picked up another 5D instead, at half the cost. Now I've got a 16 gig SD card I don't need. Maybe when the next G series model comes out.